PROJECT SUMMARY The goals of this proposal are to (1) obtain experimental skills and career training necessary to develop an independent research program investigating mechanisms of age-dependent cognitive decline and Alzheimer?s disease pathogenesis and (2) determine whether cellular senescence contributes to cerebrovascular and cognitive dysfunction. Age-related deterioration of the cerebrovasculature is an important contributor to cognitive decline and Alzheimer?s disease, but targetable underlying mechanisms have yet to be discovered. Cellular senescence has emerged as a unifying feature of aging and numerous age-related conditions. Through the senescence-associated secretory phenotype (SASP), senescent cells impair tissue structure and function. Despite the well-known relationships between age-related vascular decline and cognition, whether and how senescent cells and the SASP contribute to cerebrovascular and cognitive dysfunction has not been explored. The proposed project will use young (6 months) and aged (26 months) p16-Ink-Attac mice, in which senescent cells can be GFP-monitored or deleted. We will also test the effects of senolytic drugs, which kill senescent cells. Parallel transgenic and pharmacological elimination strategies will enable us to mechanistical- ly explore the identity and effects of senescent cells. Aim 1 will identify the cell types that senesce in brain aging and will compare transgenic and senolytic cell clearance efficiency across cell populations in vivo. Aim 2 will leverage in vivo and in vitro experiments to test the hypothesis that senescent cerebrovascular cells secrete a proremodeling and proinflammatory SASP, which promotes BBB permeability and inflammation and may be alleviated by senescent cell clearance. Aim 3 will test the hypothesis that senescent cell removal improves vasomotor and cognitive function in aged mice. The K99 phase will be conducted at Mayo Clinic and will focus on obtaining mentored training in methods required to complete the proposed aims, conducting in vitro and in vivo experiments, and publishing cell-type profiling and in vitro results. The R00 phase will be conducted in my independent lab and will focus on analyzing mouse tissues and data, publishing all in vivo findings, and developing an R01 application based on these results. The proposed plan synergizes new skills in advanced imaging, vascular physiology, and cognitive testing with prior expertise in brain aging and cellular senescence to create a research trajectory that is distinct from my mentors? foci. This work will produce a robust foundation for an independent research career elucidating cellular aging mechanisms and translatable solutions underlying cognitive decline and Alzheimer?s disease.